Heat Resistance of Listeria monocytogenes Scott A and HAL 957E1 in Various Liquid Egg Products†

1995 ◽  
Vol 58 (11) ◽  
pp. 1211-1214 ◽  
Author(s):  
F. M. BARTLETT ◽  
A. E. HAWKE
Keyword(s):  
Listeria Monocytogenes ◽  
Egg Yolk ◽  
Death Time ◽  
High Temperature Short Time ◽  
Egg Products ◽  
Liquid Whole Egg ◽  
The Individual ◽  
Thermal Death Time ◽  
Short Time ◽  
Whole Egg

The thermal destruction of Listeria monocytogenes Scott A and HAL 957E1 (an egg isolate) was determined in five liquid egg products. The egg products used were liquid whole egg (LWE), liquid whole egg with 10% NaCl (LWEN), liquid whole egg with 10% sucrose (LWES), egg yolk with 10% NaCl (EYN), and egg yolk with 10% sucrose (EYS). Each of these products was inoculated with the individual strains of L. monocytogenes at initial populations of 106 colony-forming units (CFU)/ml and exposed to temperatures of up to 70°C for various periods of time from which thermal death time (TDT) curves were constructed. The Scott A strain tended to be more heat resistant than the egg isolate, HAL 957E1. The sensitivity of both strains to heating was influenced by the type of egg product in which they were suspended. The highest rates of kill were noted in LWE, while survival was best in those products supplemented with NaCl (LWEN and EYN). For the nonsalted products, time and temperature combinations equivalent to those required for the high-temperature short-time (HTST) pasteurization of liquid egg achieved 1.7 to 4.4 log-unit reductions of L. monocytogenes populations, while reductions for the salted products were only 0.2 to 0.6 log units. These results suggest that current HTST pasteurization conditions for liquid egg will not ensure a Listeria-free product, especially with products supplemented with NaCl.

scholarly journals HOW DOES CRYOGENIC FREEZING AFFECT THE CALORIMETRIC PROPERTIES OF LIQUID EGG PRODUCTS?

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Hidas Karina Ilona ◽  
Ildikó Csilla Nyulas-Zeke ◽  
László Friedrich ◽  
Anna Visy ◽  
Judit Csonka ◽  
...  
Keyword(s):  
Liquid Nitrogen ◽  
Frozen Storage ◽  
Colour Change ◽  
Egg Yolk ◽  
Egg White ◽  
Dry Matter Content ◽  
Scanning Calorimetry ◽  
Egg Products ◽  
Liquid Whole Egg ◽  
Whole Egg

Eggs are widely utilized because of their high nutrient value, coagulating, foaming, emulsifying and sometimes even colouring or flavouring facilities in food manufacturing. Production of processed egg products shows an increasing trend. Frozen products belong to first processing, their shelf life can increase up to 1 year. By freezing, a large reduction in microbial loss can be achieved. But different undesirable processes can occur. The effect of freezing on animal cells is highly dependent on freezing parameters. It has a different effect on egg subtituents. Egg yolk undergoes a gelation process while proteins can denaturate. In our study pasteurized liquid egg products (liquid egg white, liquid egg yolk and liquid whole egg) were frozen by dripping into liquid nitrogen. After that, a 14-day frozen storage experiment was carried out at -18°C. Before freezing and on the 1th, 7th and 14th days of storage experiment pH, dry matter content, colour and calorimetric properties (denaturation temperatures and enthalpy of denaturation) with differential scanning calorimetry were tested. For statistical analysis, one-way ANOVA (α = 0.05) was employed. In our experiment, we found no significant change in calorimetric properties of liquid egg white after freezing, but significant decreasing of enthalpy and denaturation temperatures of liquid egg yolk and liquid whole egg was identified. In contrast, frozen storage had a decreasing effect in all these products. Freezing caused a clearly visible colour change in LEW, a visible change in colour of LWE and a very clearly visible change in colour of LEY. In case of LEW and LEY changes increased to clearly visible 14 days. In conclusion, our results show that frozen storage had a greater effect on liquid egg products properties than freezing in liquid nitrogen.

BACTERIOLOGICAL ASPECTS OF THE EVALUATION OF ADEQUACY OF PASTEURIZATION

1951 ◽  
Vol 14 (6) ◽  
pp. 170-172 ◽  
Author(s):  
Franklin W. Barber
Keyword(s):  
High Temperature ◽  
Dairy Products ◽  
Test Organism ◽  
Additional Information ◽  
Heat Resistant ◽  
Death Time ◽  
High Temperature Short Time ◽  
Thermal Death ◽  
Thermal Death Time ◽  
Short Time

Increased interest in high-temperature, short-time pasteurization of various dairy products has emphasized the need for methods to determine the adequacy of pasteurization. One such method is described, but there is need for additional information. The thermal death time curves of various pathogens should be determined in different dairy products. A suitable heat resistant test organism such as Micrococcus MS-102 should be selected, approved by health officials and made available to others for controlled studies. Data should be accumulated so that curves could be prepared to show any combination of time and temperature which would result in adequate pasteurization.

Behavior of Psychrotropic Pathogens Listeria monocytogenes, Yersinia enterocolitica, and Aeromonas hydrophila in Commercially Pasteurized Eggs Held at 2, 6.7 and 12.8° C.

1992 ◽  
Vol 55 (1) ◽  
pp. 8-12 ◽  
Author(s):  
JOHN P. ERICKSON ◽  
PHYLLIS JENKINS
Keyword(s):  
Listeria Monocytogenes ◽  
Yersinia Enterocolitica ◽  
Aeromonas Hydrophila ◽  
Egg Yolk ◽  
Egg White ◽  
Competitive Growth ◽  
Growth Responses ◽  
Egg Products ◽  
Spoilage Microflora ◽  
Whole Egg

Four commercially pasteurized liquid egg products were individually inoculated with Listeria monocytogenes, Yersinia enterocolitica, and Aeromonas hydrophila. They were unsalted whole egg blend, unsalted egg white, 5% NaCl whole egg blend, and 10% NaCl egg yolk. The inoculated samples and uninoculated controls were held at 2, 6.7, and 12.8°C (temperature abuse) for 14 d. Psychrotropic pathogen growth or survival risks in the unsalted and NaCl supplemented eggs were Y. enterocolitica > A. hydrophila > L. monocytogenes, and L. monocytogenes > Y. enterocolitica > A. hydrophila, respectively. Y. enterocolitica produced delayed (≥4 d) growth responses in unsalted eggs held at ≤6.7°C but was inhibited by ≥5% NaCl at all three holding temperatures. L. monocytogenes growth was prevented at ≤6.7°C in the unsalted and NaCl supplemented eggs. The organism rapidly increased in the temperature abused 5% NaCl whole egg blend. L. monocytogenes and A. hydrophila were inactivated in the unsalted egg white and NaCl supplemented eggs, respectively. Psychrotropic pathogen behavior was unaffected by the competitive growth of indigenous spoilage microflora including pseudomonads, Serratia spp., and NaCl tolerant micrococci. Properly refrigerated and hygienically handled pasteurized liquid eggs are microbiologically safe against a broad range of psychrotropic pathogen strains.

Nisin Reduces the Thermal Resistance of Listeria monocytogenes Scott A in Liquid Whole Egg

1999 ◽  
Vol 62 (9) ◽  
pp. 999-1003 ◽  
Author(s):  
KELLEY P. KNIGHT ◽  
FRANCIS M. BARTLETT ◽  
ROBIN C. McKELLAR ◽  
LINDA J. HARRIS
Keyword(s):  
Heat Treatment ◽  
Listeria Monocytogenes ◽  
Logistic Equation ◽  
Glass Ampoule ◽  
Log Reduction ◽  
Egg Products ◽  
Current Minimum ◽  
Liquid Whole Egg ◽  
D Values ◽  
Whole Egg

D-values (decimal reduction times) and z-values (increase in temperature required for a 1-log change in D-value) for Listeria monocytogenes Scott A were determined in liquid whole egg with nisin (0 or 10 μg ml−1) and NaCl (0 or 10%) by a submerged glass ampoule procedure. Samples were plated onto nonselective agar at appropriate intervals, and D-values were determined using a modified biphasic logistic equation. Addition of NaCl increased D-values at all temperatures tested. The addition of nisin to unsalted liquid whole egg resulted in a rapid 4-log reduction in viable counts within the first hour. Nisin significantly (P ≤ 0.05) decreased D-values at lower (<58°C) temperatures in both unsalted and salted liquid whole egg but had little effect on the D-values at current minimum U.S. and Canadian pasteurization temperatures (60°C without NaCl; 63°C with NaCl). However, when nisin was added 2 h prior to heat treatment, D-values were significantly (P ≤ 0.05) reduced at these temperatures. Inhibitory levels of nisin were detected in the liquid whole egg postpasteurization. Nisin could have a favorable impact on the control of L. monocytogenes in pasteurized liquid egg products.

scholarly journals Effect of high hydrostatic pressure at 400 MPa on quality attributes of liquid egg products

2016 ◽  
Vol 5 (1-2) ◽  
pp. 148-152
Author(s):  
Adrienn Tóth ◽  
Csaba Németh ◽  
Réka Juhász ◽  
Ildikó Zeke ◽  
Salamon Bertold ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Egg Yolk ◽  
Rotational Viscometer ◽  
Egg Products ◽  
Thixotropic Behavior ◽  
Liquid Whole Egg ◽  
Whole Egg ◽  
One Way Anova ◽  
Shearthinning Behavior

Samples prepared from liquid egg yolk (LEY), liquid egg white (LEW) and liquid whole egg (LWE) were processed by high hydrostatic pressure (HHP) using different holding times (60, 180, 300, 420 and 600 s). The aim of our experiment was to examine how different holding times influences technofunctional attributes of liquid egg products. The color of samples changed after 60 s HHP treatment, but visible changes were evaluated just after 180­ 300 s. The pH of samples was stable, there were no significant changes caused by HHP (one-way ANOVA, a=0,05). The apparent viscosity was measured by a rotational viscometer as a function of shear rate. The shearthinning behavior of LEY and pseudopastic behavior of LEW and LWE were fitted well into HerschelBulkley model (with a satisfying correlation of R2 > 0.96). For the selected shearing rate, viscosity was measured in relation to shearing time. Thixotropic behavior of samples was increased by longer holding time of HHP treatments.

Development of an Effective Two-Step Enrichment Process to Enhance Bax System Detection of Healthy and Injured Salmonella Enteritidis in Liquid Whole Egg and Egg Yolk

2020 ◽  
Vol 83 (3) ◽  
pp. 397-404
Author(s):  
SHISHI HUANG ◽  
TAY BOON HUI ◽  
HYUN-GYUN YUK ◽  
QIANWANG ZHENG
Keyword(s):  
False Negative ◽  
Brain Heart Infusion ◽  
Egg Yolk ◽  
Target Cells ◽  
Detection Accuracy ◽  
Egg Products ◽  
Liquid Whole Egg ◽  
Inhibitory Components ◽  
Enrichment Process ◽  
Whole Egg

ABSTRACT The BAX system for pathogen detection has been highly accurate in a variety of food products. However, false-negative results have been reported for the detection of pathogens in liquid egg products because of failed pathogen resuscitation and the existence of inhibitory components. In this study, a short-time enrichment step was used to simultaneously resuscitate the target cells to the detection level and to dilute the inhibitory components to reduce detection interference. The MP medium (BAX system) enabled faster multiplication of healthy Salmonella cells than did buffered peptone water (BPW) in tested liquid whole egg and egg yolk. However, MP failed to resuscitate heat-injured cells even after 24 h of incubation. Therefore, MP was replaced with BPW as the enrichment broth for the BAX system. However, the use of BPW for a one-step enrichment was not effective for removal of PCR inhibitors in egg yolk, and unstable detection results were obtained. To improve detection accuracy, a second step of enrichment with brain heart infusion was added. This two-step enrichment process shortened the enrichment time to 14 h and greatly increased the number of samples in which the pathogen was detected during the same enrichment time, especially in the liquid egg yolk samples. The validation study revealed 100% diagnostic accuracy of the two-step enrichment process plus the BAX system. These results indicate that a two-step enrichment process added to the BAX system can improve the detection of pathogenic Salmonella in liquid egg products. HIGHLIGHTS

Performance of Several Enrichment Media in the Isolation of Salmonellae from Liquid Egg Products

1984 ◽  
Vol 47 (3) ◽  
pp. 217-219 ◽  
Author(s):  
M. YDE ◽  
G. GHYSELS
Keyword(s):  
Comparative Study ◽  
Egg Yolk ◽  
Selective Enrichment ◽  
Egg Products ◽  
Liquid Whole Egg ◽  
Whole Egg

Ninety-seven samples of raw liquid whole egg and egg yolk were analyzed for the presence of Salmonella; 51 samples (52%) were found positive. A comparative study was conducted on the performance of seven selective enrichment procedures in the isolation of Salmonella from liquid egg products: selenite-cystine broth incubated at 37°C and 43°C, Muller-Kauffmann tetrathionate broth at 43°C, modified Rappaport medium RIO/100 and RIO/10 also incubated at 43°C, the experimental broth of Greenwood et al. incubated at 37° and 43°C. The best results were obtained with tetrathionate broth which detected 96% of all positive samples. Differences in the rate of isolation by the tetrathionate broth, selenite-cystine broth, modified Rappaport medium RIO/100 and the experimental broth of Greenwood et al., all incubated at 43°C, were not significant as determined by paired χ2 test. Minor results were obtained with selenite-cystine broth and the experimental broth of Greenwood et al., both incubated at 37°C. Modified Rappaport medium RIO/100 proved to be more efficient than RIO/10.

scholarly journals Influence of the Initial Cell Number on the Growth Fitness of Salmonella Enteritidis in Raw and Pasteurized Liquid Whole Egg, Egg White, and Egg Yolk

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1621
Author(s):  
Silvia Guillén ◽  
María Marcén ◽  
Ignacio Álvarez ◽  
Pilar Mañas ◽  
Guillermo Cebrián
Keyword(s):  
Salmonella Enteritidis ◽  
Growth Parameters ◽  
Egg Yolk ◽  
Egg White ◽  
Cell Number ◽  
Initial Number ◽  
Initial Cell ◽  
Egg Products ◽  
Liquid Whole Egg ◽  
Whole Egg

Salmonella growth in egg and egg products has been widely studied, but there are still some aspects that are not fully known. The objective of this work was to study the influence of the initial cell number on the growth fitness of Salmonella Enteritidis in raw and pasteurized egg products. Growth curves of five Salmonella Enteritidis strains in raw and pasteurized egg products, starting from different initial numbers, were obtained and fitted to the Baranyi and Roberts model. The results revealed that lower initial numbers led to longer lag phases (λ) and lower maximum specific growth rates (μmax) in raw liquid whole egg. Similar results were observed in raw egg white (except for one strain). Conversely, no influence (p > 0.05) of the initial concentration on Salmonella growth parameters in raw egg yolk was observed. On the other hand, no influence of the initial number of cells on Salmonella growth fitness in commercial pasteurized liquid whole egg was observed. The results obtained demonstrate that the disappearance of this initial-dose dependency phenomenon was dependent on the intensity of the thermal treatment applied. Finally, the influence of the initial number was, in general, lower in pasteurized than in raw egg white, but large differences among strains were observed.

Membrane Damage and Viability Loss of Escherichia coli K-12 and Salmonella Enteritidis in Liquid Egg by Thermal Death Time Disk Treatment†

2008 ◽  
Vol 71 (10) ◽  
pp. 1988-1995 ◽  
Author(s):  
DIKE O. UKUKU ◽  
TONY JIN ◽  
HOWARD ZHANG
Keyword(s):  
Salmonella Enteritidis ◽  
Membrane Damage ◽  
E Coli ◽  
Viability Loss ◽  
Death Time ◽  
Thermal Death ◽  
Liquid Whole Egg ◽  
K 12 ◽  
Thermal Death Time ◽  
Whole Egg

Bacterial injury, including leakage of intracellular substance and viability loss, of Escherichia coli K-12 (ATCC 23716) and Salmonella Enteritidis (ATCC 13076) inoculated in liquid egg white and liquid whole egg was determined by thermal death time disk. E. coli K-12 and Salmonella Enteritidis were inoculated in liquid egg white and liquid whole egg to a final count of 7.8 log CFU/ml and were thermally treated with thermal death time disks at room temperature (23°C), 54, 56, 58, and 60°C from 0 to 240 s. Sublethal injury, leakage of intracellular substances, and viability loss of E. coli K-12 and Salmonella Enteritidis was investigated by plating 0.1 ml on selective trypticase soy agar containing 3% NaCl, 5% NaCl, sorbitol MacConky agar, and xylose lysine sodium tetradecylsulfate and nonselective trypticase soy agar. No significant (P >0.05) differences on percent injury or viability loss for E. coli K-12 and Salmonella populations were determined in all samples treated at 23°C. Sublethal injury occurred in E. coli and Salmonella populations at 54°C or above for 120 s. Viability losses for both bacteria averaged 5 log at 54°C or above for 180 s, and the surviving populations were below detection (<10 CFU/ml). Thermal treatment at 40°C and above led to membrane damage, leakage, and accumulation of intracellular ATP from 2 to 2.5 log fg/ml and UV-absorbing substances of 0.1 to 0.39 in the treated samples. These results indicate similar thermal injury/damage on both E. coli and Salmonella membranes as determined by the amount of inactivation, viability loss, and leakage of intracellular substances of bacteria.

Factors Influencing Survival of Listeria monocytogenes in Milk in a High-Temperature Short-Time Pasteurizer

1992 ◽  
Vol 55 (12) ◽  
pp. 946-951 ◽  
Author(s):  
J. M. FARBER ◽  
E. DALEY ◽  
F. COATES ◽  
D. B. EMMONS ◽  
R. McKELLAR
Keyword(s):  
High Temperature ◽  
Listeria Monocytogenes ◽  
Most Probable Number ◽  
Probable Number ◽  
High Temperature Short Time ◽  
Whole Milk ◽  
Different Temperatures ◽  
Margin Of Safety ◽  
Short Time ◽  
Adequate Margin

Heat resistance experiments were carried out with Listeria monocytogenes which had been grown at three different temperatures (30, 39, and 43°C). Heated whole milk was inoculated with L. monocytogenes and then passed through a high-temperature short-time system at 72, 69, 66, and 63°C for a minimum holding time of 16.2 s. Heated cells were recovered both aerobically and anaerobically using four different methods: direct plating, most probable number, cold enrichment, and warm enrichment. Significant differences in recovery of L. monocytogenes were observed depending on the growth temperature. Cells grown at 43, 39, or 30°C, held 1 d at 4°C, and then heated at 69°C showed an overall decrease in numbers of approximately 2.1, 2.8, and 4.1 logs, respectively. Cells grown at 39°C and then held 3 d at 4°C appeared to be the most heat sensitive. Although cells grown at 43 and 39°C were capable of surviving at the minimum high-temperature short-time temperature (72°C), those grown at 30°C were not. In some instances, anaerobic incubation enhanced the recovery of L. monocytogenes, as compared to cells recovered aerobically, although these differences were not statistically significant. While L. monocytogenes can survive minimum pasteurization treatment (71.7°C/16 s) under certain conditions, common methods of handling, processing, and storing fluid milk will provide an adequate margin of safety.

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